How are side bands produced?

Solution

When the audio frequency modulating signal wave is superimposed on a high frequency wave called carrier wave, the modulation process produce frequencies that are the sum and difference of carrier and modulating frequencies. These frequencies are side bands.
Lower side band frequency = $f subscript c space minus space f subscript m$
Upper side band frequency = $f subscript c space plus space f subscript m$
where,
$f subscript c$ is the carrier wave frequency and
$f subscript m$ is the modulating/audio signal frequency.